watch face issues - blacked out

Not seen that before. Is it a stock watch face?

yes indeed - you can access these options through menu -> watch face -> Add new, then your can select an analogue or digital watch face and start customization accordingly. The issue is for most watch faces with second hands from what I have experienced so far. It also happens on digital watch faces too. I'm using New Qbak Analog as it keeps the watch face running perfectly. 

Are you on 11.75? I have seen the same problem on my F6, seen one time. But a standard Reboot is enough at my side. 

I've had the issue since I got it - firmware was on 9 then if I'm not mistaken. I did a few reboots and a full factory reset. This thing just won't go away. some watch faces don't have that but all of the default ones have that issue, some get the full screen blacked out. To elaborate that black screen moves in cycles covering most or part of the screen.

Remove the added watch faces and then see if occurs with the stock faces. Try a hard reset - press and hold top left through the alert screen until power off.

However, you might need to do a full reset to thoroughly clear the added ones. If you still have issues following a full reset back to factory defaults then you should contact Garmin.

If it happens only with the watchfaces that have seconds, the screen is faulty and you will need to send it in assistance. 

Thank you Raul, I'm contacting support as have a chance for a few updates to come through beforehand. It feels like a software glitch. How certain are you that it's a hardware issue?

It happened to me and it was a faulty display, not a software issue.

Great - thank you